This proposal is for continued development and clinical utilization of our current radioimmune assay technique separately for delta 9-tetrahydrocannabinol (THC) and its significant metabolites. For greater sensitivity and simplicity new immune assays are to be done utilizing our synthesized drug marker haptens. The principles employed in these assays and in preparing the markers should be widely applicable to numerous drugs and their metabolites such as 11-nor-9-carboxy-delta 9-THC and heroin for which homologous markers of adequate specific activities are not currently available.